Use specific Allow-Origins header

## What
Currently in the cdk deployment and in all lambda handlers the `Allow-Origins` headers are set to `*`. It should be `localhost:3000` for local mode and `app.takeniftynotes.net` for production.

## How
Change the header in the cdk api construct in [cdk/rocketnotes.go](https://github.com/fynnfluegge/rocketnotes/blob/main/cdk/rocketnotes.go) and in all lambda-handlers in `lambda-handler/`.